It has been known that viruses having a lipoid sheath are relatively sensitive and, thus, can be inactivated by virucidal disinfectants known so far. In contrast thereto, greater problems are caused by naked viruses, which are substantially more stable against conventional disinfectants and which can be inactivated only with relatively high concentrations of formaldehyde. However, formaldehyde is undesirable because of toxicity and does not allow the disinfection of contaminated parts of the body to be effected in either the clinic or the laboratory.
The literature on the disinfecting and inactivating activity of commercially available skin-compatible disinfectants is contradictory. Also the statements on the activities of alcohols are contradictory. Investigations on the activity of isopropanol against naked viruses, for example, have shown that this alcohol is only very weakly active or inactive. These investigations have further shown that ethanol and methanol are highly active if they contain less than 30 of water. Thus, German application OS 34 30 709 of Applicants shows a virucidal agent against naked viruses which consists of at least 70% of methanol and/or ethanol and from 1 to 10% of glycerol. This virucidal agent may additionally contain up to 5% of castor oil. Thorough investigations of these virucidal agents based on methanol and/or ethanol containing additives of glycerol and castor oil with a broad-spectrum of naked viruses, however, have resulted in the finding that these agents fail to be effective against certain kinds of problematic viruses, such as adenovirus 2 (strain Adenoid 6) and SV 40-virus (e.g. strain 777).
From German application OS 32 27 126 it is known that propagation of respiratory viruses can be interrupted or prevented by contacting the viruses with a short-chain organic acid. Citric acid, malic acid, succinic acid and benzoic acid as well as substituted derivatives thereof were mentioned as preferred organic acids. Furthermore it was indicated that the activity can be improved by surfactants, with the sodium salt of 1,4-bis(2-ethylhexyl)ester of sulfosuccinic acid and sodium dodecylsulfate being preferred. Said agents are active against the usual respiratory viruses such as rhinoviruses, parainfluenza viruses and adenoviruses. In prepared use these acids are applied, optionally together with the wetting agent, onto cellulose fabric or textiles. As further administration forms there have been mentioned nose sprays, face creams, hand lotions and lipsticks.
From the experimental results as set forth therein it is apparent that these acid-containing agents exhibited some activity also against adenovirus 5; however, in many cases a reduction by only two powers of ten or 99% was observed, and in part this was accomplished only after 5 minutes of action and/or at relatively high concentrations.
The Deutsche Vereinigung zur Bekampfung von Viruskrankheiten (German Association for Combatting Virus Diseases) and the Bundesgesundheitsamt (Federal Health Office) are elaborating new regulations, according to which an agent may carry the designation virucidal agent only in the case that it is capable of inactivating the following four virus strains within a period of time which is appropriate for the intended use, e.g. for disinfecting a person's hands within from one to two minutes: poliovirus 1 (strain Mahoney), vacciniavirus (strain Elstree), SV 40-virus (e.g. strain 777) and adenovirus 2 (strain Adenoid 6). Thus, it is demanded that only those agents which have a broad-spectrum activity are allowed to be called virucidal agents.